多视点自由立体投影系统

利用双柱面光栅的成像原理,自由立体投影系统将具有视差的画面分别成像于不同的空间区域,在成像区域形成一系列立体图像窗口,构成多视点自由立体成像。在我们设计的自由立体投影系统中,采用了四台高分辨率投影机,通过对1.5m(60英寸)双柱面投影屏幕的设计,形成了主成像窗口与副成像窗口有机拼接的宽视角(±30°)立体投影系统。经过模拟分析在不同参数条件下投影系统的空间光照度分布情况,直观地验证了上述投影系统的成像理论。     

基于视差空间运动估计的高精度立体视觉定位

立体视觉定位算法的运动估计通常在3D欧式空间中进行,但由于特征点3D坐标的噪声各向异性且分布不均匀,3D重建在深度方向上比另两个方向上的准确性差,从而导致3D欧式空间运动估计精确不高.本文提出了一种新的基于视差空间运动估计的高精度立体视觉定位算法.算法首先采用视差空间4点闭环线性解法和RANSAC算法得到初始鲁棒运动估计和匹配内点.接着,利用新的视差空间再投影误差函数提出了基于LM算法的视差空间运动参数非线性优化方法,对初始运动参数进一步优化.视差空间噪声分布均匀且各向同性,本文的初始运动参数线性估计和非线性优化都在视差空间中进行且能达到全局最小.仿真实验和真实实验结果表明,本文算法能得到高精度的立体视觉定位结果,优于传统的3D欧式空间运动估计方法.     

立体显示系统设计中人的因素

立体显示系统是基于双眼视差设计的以体视方式呈现三维信息的系统。文章从工效学的角度对立体显示系统设计中视差极限、立体视锐、图像间距、分离方向、视距、瞳距以及刺激间的知觉交互作用等影响其显示质量的因素作了简要分析。据此提出立体显示系统设计应尽力避免由双眼竞争、立体空间失真以及Pul frich现象所造成的不良影响,旨在为优化系统设计提供参考。     

平视显示器视差自动测量技术研究

平视显示器是一种大视场大出瞳的光学系统,常用的测视差的方法是摆头法,但测量精度较低,并且有人眼读数误差。为了提高平视显示器视差的调校精度及效率,消除人眼读数误差,介绍了一种基于CCD视频图像处理的视差自动测量系统。用CCD像机对平视显示器图像画面进行采集,在出瞳的范围内进行平移,比较在出瞳边缘采集的图像,计算两幅图像的偏移量,自动得出平视显示器的视差。详细论述了该方法的测量原理,并对该视差测量仪的光机结构进行了详细说明,对各技术参数的选择进行了分析,对测量精度进行了分析,最后对几种视差测试精度进行了对比分析。     

采用色彩相似性约束的立体匹配

在立体匹配算法中引入色彩相似性约束条件.首先加入权值模板来对用于灰度空间匹配的SSD算法进行改进,在抑制噪声的同时,可以最大程度的保持景物的细节信息,从而有效的解决SSD算法对于噪声比较敏感的问题.然后引入色彩相似性约束将灰度空间的匹配和彩色空间的匹配有机的结合起来,大大提高了匹配的精度.实验结果表明,该算法能够合理利用彩色立体像对中的色彩信息,从而生成准确度较高的视差图,是一种有效的立体匹配方法.     

双目立体显微测量的研究

双目立体视觉是计算机视觉的一个重要分支,即由构成一定角度的两台摄象机拍摄同一幅画面,通过计算空间点在两幅图像中的视差,获得该点的三维坐标值.提出将双目立体计算机视觉技术应用于光学立体显微镜上,可对一些微小物体进行观测和测量,并获取深度信息,建立三维图象,从而用简便、经济的手段进行微小物体的三坐标测量.     

基于区域分割的动态规划立体匹配算法

提出一种基于区域分割的动态规划立体匹配算法.首先参考图像经自适应多阈值切割之后,得到一个由区域组成的集合,并沿着各个闭合区域的边界进行动态规划跟踪,然后对于非匹配区域和区域内部分别作视差融合和视差插值处理,获得最终的稠密视差图.实验结果表明,该算法能够取得较为理想的效果,视差图横向“条纹”瑕疵和边界区域上的误匹配点明显减少,层次更加分明,整个视差图平滑性较好,匹配效率有了显著提高.     

基于双目相机的光栅立体印刷图像合成

目的研究一种基于双目相机的光栅立体图像合成方法。方法首先用双目相机采集场景中2个观察角度的二维平面图像数据。基于双目立体视觉理论,采用一种鲁棒性较强的基于区域分割的图像匹配方法,得到精度较高的深度图。然后分析序列视差图像的成像模型,建立一种基于双目图像对生成序列视差图像的方法,得到连续角度等间隔的序列图像。最后基于柱镜光栅的光学特性形成的立体印刷图像编码规则,对序列视差图像进行纵向条纹抽样分割,等间隔的抽取每幅序列视差图像中的对应列实现光栅立体图像的合成。结果验证了该光栅立体图像合成方法的有效性。结论基于双目相机的光栅立体合成方法,可以使立体印刷产品实现个性化、便捷化的即时输出。     

3D影视作品观看舒适度问题的探讨

本文根据人眼对立体环境的感知过程、分析视差图几何尺寸和形态差异、指出作品必须遵循人的立体视觉规律,并讨论了立体影视作品的蒙太奇处理原则和3D影视作品的放映与显示。     

基于DLP投影的自由立体显示视区分析

为了获得低成本大屏幕自由立体显示器,采用了DLP投影的技术方案.通过模拟柱透镜光路,分析了立体视区特性.按照自由立体显示的结构和原理,计算出立体视区光能分布图.理论上证明了在最佳观看距离可获得没有互扰的立体影像.研究了最佳观看距离和像素匹配的设定方法,给出观看较好立体效果的范围.立体视区的研究协助了立体显示器的设计,最终获得了具有较好立体感和临场感的150英寸大屏幕立体显示器.     

Efficient depth map compression for view rendering in 3D video

Abstract

A depth map represents three-dimensional (3D) scene information, which is used to synthesise virtual views in 3D video coding. Since the quality of synthesised virtual view highly depends on the quality of depth map, efficient depth coding is crucial for the 3D video system. However, depth map is not directly used for display but to generate virtual views. Compressing depth map using existing video coding techniques yields unacceptable distortions in rendered virtual view. Thus, the depth map needs to be compressed in a way that can minimise distortions in the rendered views. To solve this problem, we propose an efficient depth map compression method for view rendering based on view rendering distortion other than depth map distortion itself. Firstly, we derive relationship between distortion in coded depth map and the rendered view. Then, a region-based video characteristic distortion model is proposed to precisely estimate distortion in view synthesis. Finally, a multilateral filtering is applied as an in-loop filter to reduce rendering artefacts. Experimental results show that the proposed method achieves 2 dB coding gain in terms of PSNR and subjective quality improvement of synthesised views.     

Content- and disparity-adaptive stereoscopic image retargeting

The paper proposes a content- and disparity-adaptive stereoscopic image retargeting. To simultaneously avoid the saliency content and disparity distortion, firstly, we calculate the image saliency region distortion difference, and conclude the factors causing visual distortion. Then, the proposed method via a convex quadratic programming can simultaneously avoid the distortion of the salient region and adjust disparity to a target area, by considering the relationship of the scaling factor of salient region and the disparity scaling factor. The experimental results show that the proposed method is able to successfully adapt the image disparity to the target display screen, while the salient objects remain undistorted in the retargeted stereoscopic image.     

Computer-generated holograms of a real three-dimensional object based on stereoscopic video images

A novel method of using stereoscopic video images to synthesize the computer-generated hologram (CGH) patterns of a real 3D object is proposed. Stereoscopic video images of a real 3D object are captured by a 3D camera system. Disparity maps between the captured stereo image pairs are estimated and from these estimated maps the depth data for each pixel of the object can be extracted on a frame basis. By using these depth data and original color images, hologram patterns of a real object can be computationally generated. In experiments, stereoscopic video images of a real 3D object, a wooden rhinoceros doll, are captured by using the Wasol 3D adapter system and its depth data are extracted from them. Then, CGH patterns of 1280 pixels x 1024 pixels are generated with these depth-annotated images of the wooden rhinoceros doll, and the CGH patterns are experimentally displayed via a holographic display system.     

fMRI analysis of excessive binocular disparity on the human brain

The aim of this study is to evaluate brain regions related with excessive binocular disparity that may be linked to stereoscopic visual fatigue. In stereoscopic displays, excessive binocular disparity may generate blurring or double vision in the stereovision and induce unnatural oscillations in accommodation and vergence. These phenomena may lead to visual fatigue and activation (or deactivation) of human brain related with sensory and eye movement functions. A functional magnetic resonance imaging (fMRI) method is used to investigate the effect of excessive binocular disparity on human brain. Subjective assessments of visual fatigue are also conducted with the same stimuli as the fMRI experiment. Based on the subjective assessment results, participants are classified into low‐ and high‐fatigue groups. From the fMRI experiments, the high‐fatigue group showed more activation at the intraparietal sulcus (IPS) than the low‐fatigue group, when viewing an excessive disparity stimulus. The results showed that the excessive binocular disparity stimulus may induce overload to the IPS region, which is related with stereo processing and saccadic eye movement. In addition, it could be possible to use fMRI as an objective measurement method for understanding the stereoscopic visual fatigue when stimuli with excessive binocular disparity are applied.     

Multiview foreground extraction and composition to multiview background using trimap sharing for natural 3D scene generation

Digital matting for extracting foreground objects from an image is an important process to generate special effects in the movie industry and the broadcasting center. Recently, a digital matting algorithm has been developed to create an alpha matte using a well‐focused image generated from multiview images. However, this method could generate only a single‐view alpha matte, even though it used multiple cameras. In this article, we propose a new estimation scheme for multiview alpha mattes by sharing the trimap of the reference view. Furthermore, we use the motion vector to update the trimap for video matting. After we extract foreground objects from all view images, we composite the foreground objects with the corresponding background images captured in the same multiview camera arrangement. Experimental results demonstrate that multiview composite images can generate reasonably natural 3D views through the stereoscopic monitor. © 2010 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 20, 285‐293, 2010     

基于小波图像融合的非对称失真立体图像质量评价方法

通过研究非对称失真立体图像人眼视觉感知特性,提出了一种基于小波图像融合的非对称失真立体图像质量客观评价方法.首先,采用固定尺寸块匹配方法得到原始立体图像块视差值,接着,根据该视差值的大小,同时结合非对称失真立体图像视觉感知特性,对匹配块进行小波融合得到原始融合图像和失真融合图像.最后,通过计算原始融合图像和失真融合图像...     

Defocus from depth for defocus measurement

A novel method is proposed for defocus map estimation. It is based on the defocus origin that is essentially the reverse of depth from defocus (DFD). The main relations among image defocus, sensor defocus, and scene defocus for an imaging system are introduced. A defocus map is deduced from the depth map and the depth map is derived from the disparity map. The full disparity map can be reconstructed using an image-matching method and our clustering segmentation algorithm. Experimental results for an interior scene and an outdoor scene demonstrate that our method is effective in defocus measurement.     

Autostereoscopic three-dimensional display based on two parallax barriers

An autostereoscopic three-dimensional (3D) display composed of a flat-panel display, two parallax barriers, and a backlight panel is proposed. Parallax barrier 1, located between the backlight panel and the flat-panel display, divides the lights to create the perception of stereoscopic images. Parallax barrier 2, located between the flat-panel display and the viewers, acts as the function of decreasing the cross talk of the stereoscopic images. The operation principle of the display and the calculation equations for the parallax barriers are described in detail. An autostereoscopic 3D display prototype is developed. The prototype presents high-quality stereoscopic images. At the optimal viewing distance, it presents stereoscopic images without cross talk. At other viewing distances, it has less cross talk than a conventional autostereoscopic 3D display based on one parallax.     

The range of stereoscopic perception: influence of binocular summation,interocular differences in optical quality and halo perception

The study of the visual function and optical quality of the eye has become a fundamental aim in the characterization of visual performance, especially in binocular vision, as this is our natural state of visual perception and because of its importance in clinical applications. Interocular asymmetry affects visual performance, and therefore its effect on different visual functions and stereopsis is of interest. In this work, we analyse interocular differences in optical quality (higher order aberrations and Strehl ratio) on the maximum disparity (the total range of stereoscopic perception) under mesopic conditions. We also analyse the relationship between the maximum disparity and the visual-discrimination capacity (halo perception) or binocular summation. The results in normal observers show a deterioration of the range of stereoscopic perception with the interocular differences in optical quality and with a higher perception of halos. Regarding the binocular summation for the visual functions studied, a positive correlation with the maximum disparity is found.     

外置式非标准视频同步信号发生器的设计

采用TMS320F206作为USB接口芯片PDIUSBD12的控制器,实现对高速数据采集卡的同步控制。主机从荻得的非标准视频数据中提取同步信号参数,通过USB接口及时传输给DSP,DSP对分频系数实行模糊控制,产生精度可达7ps的视频同步信号,实现非标准视频信号的采集和稳定显示。分别对行频为15．625kHz、场频为50Hz的CCD视频信号,及行频为48．656kHz、场频为60Hz的计算机显示器视频泄漏信号进行了采集与显示,证实了此方案的可行性。